Motor fuel containing octane appreciator



United States Patent 3,087,801 MOTOR FUEL CONTAINING OCTANE APPRECIATOR George W. Eckert, Wappingers Falls, and Harry Chafetz,

Poughkeepsie, N.Y., assignors to Texaco Inc, a corporation of Delaware No Drawing. Filed Jan. 27, 1959, Ser. No. 789,229

8 Claims. (Cl. 4469) This invention relates to a hydrocarbon fuel composition of high octane rating. More specifically, it involves the discovery that the octane rating of leaded gasoline fuels of prescribed composition is substantially improved by the addition of ether esters containing the ether group and the acyloxy group attached to the same carbon atom.

The recent increases in compression ratios of automobile engines have place a severe strain on petroleum refiners to produce fuels having the octane rating demanded by these engines. Premium fuels at the present time have research octane ratings between 97 and 100 and it has been predicted that premium fuels will have to have octane ratings between 105 and 110 five years from now in order to satisfy the octane requirements of the high compression automotive engines predicted for that date. In order to produce premium fuels of octane ratings of 95 and above, it has been necessary 'for refiners to rely heavily on catalytic refining operations such as fluid catalytic cracking, catalytic reforming, alkylation and catalytic isomerization.

Catalytic cracking and catalytic reforming, which are the most widely used refining operations in the production of high octane fuels, produce substantial quantities of aromatics; catalytic cracking also produces a substantial amount of olefins. It is well known that olefins and aromatics, although possessing high octane ratings, have a poorer response to organo-lead compounds such as tetraethyl lead than saturated aliphatic gasoline components. Accordingly, as the aromatic and olefinic content of the gasolines have increased to meet the octane levels required by modern automotive high compression engines, the lead response of the resulting fuels has diminished. Stated another way, the octane increment obtainable by the addition of an organo-lead compound decreases as the aromatic and olefin contents of the base fuel increase. The subject invention involves the discovery that the octane rating of leaded motor fuels containing a substantial concentration of high octane components, that is, aromatic, olefins and mixtures thereof, is markedly improved by the addition of a small amount of ether esters of prescribed composition.

In copending application, Serial No. 699,944, filed December 2, 1957, and now abandoned, it is disclosed that t-alkyl esters of monocarboxylic acids substantially raise the octane rating of a motor fuel containing an organo-lead anti-knock agent and a substantial concentration of high octane components which may be aromatic hydrocarbons, olefinic hydrocarbons or mixtures thereof. The subject invention involves the discovery that monocarboxylic acid esters of ether alcohols having IQC hydrocarbons or mixtures thereof, an organo-lead antiknock agent, and an ether ester containing the ether group and the acyloxy group attached to the same carbon atom. The ether ester is present in a minimum concentration of 0.1 volume percent in the motor fuel of the invention.

The action of ether esters having the ether radical and the acyloxy radical attached to the same carbon atom, hereafter designated 1,1-ether esters, in appreciating the octane rating of gasoline is characterized by several unusual features. In the first instance, the 1,1-ether esters appear to be ineffective in raising the octane rating of gasoline unless an organo-lead anti-knock agent, normally TEL is a component of thegasoline mixture. The second unusual characteristic of the action of 1,1-ether esters in appreciating the octane rating of gasolines is the fact that an equivalent concentration of ester appears to cause a greater octane improvement above the 100 octane level than below the 100 octane level. The third unusual feature of the action of 1,1-ether esters is that they appear to have substantially no effect on the octane rating of a gasoline consisting essentially of saturated aliphatic hydrocarbons even though an organo-lead anti-knock agent is present.

Since organo-lead anti-knock agents exert their greatest octane appreciation in predominantly saturated paraiiinic base hydrocarbon gasolines and have the least effect on the octane rating of aromatic and olefin-rich gasolines, the present invention neatly complements tetraethyl lead as an octane improver. 1,1-ether esters have their minimum effect where tetraethyl lead has its maximum effect and exert their maximum effect on octane values where tetraethyl lead has its minimum effect.

The novel fuel compositions of this invention have a minimum concentration of aromatic and/or olefin components of at least 10 volume percent. The aromatic and/ or olefin components of the motor fuel of the invention can constitute as high as 100 volume percent thereof, but usually comprise between 20 and volume percent. The minimum 10 percent concentration is necessary for 1,1-ether esters to exert a significant octane improvement.

The aromatic components of the motor fuel of the invention are generally supplied by catalytic reforming or catalytic cracking operations. Catalytic reformate is particularly high in aromatics. The olefin components of the motor fuel of the invention are derived either from thermal cracking, catalytic cracking or polymerization.

The organo-lead reagent necessary for the action of 1,1-ether esters as octane improvers is a tetraalkyl lead compound of the class known to possess anti-knock action. Tetraethyl lead is universally used as an anti-knock agent but other tetraalkyl lead compounds such as tetramethyl lead, tetrabutyl lead, tetraamyl lead, tetrapropyl lead, etc., possess anti-knock properties and may be used in the fuel compositions of the invention in conjunction with 1,l-ether esters.

The tetraethyl lead mixtures commercially available for automotive use contain an ethylene chloride-ethylene bromide mixture as a scavenger for removing lead from the combustion chamber in the form of volatile lead halides. Tetraethyl lead fluid, the commercial product, comprises tetraethyl lead, ethylene chloride and ethylene bromide, the latter two reagents being present in 1.0 theory and 0.5 theory, respectively, theory denoting the stoichiometric amount required for reaction with the lead content of the tetraethyl lead.

The organo-lead reagent is present in the fuel com positions of the invention in concentrations between 0.5 ml. per gallon up to the statutory limit of organo-lead reagent concentration which, at the present time, is 3 ml. per gallon in the case of automotive fuel and 4.6 ml. per gallon in the case of aviation fuel. The usual concentration of tetraethyl lead is between .1 and 3 ml. per gallon in automotive gasoline and 2 to 4.6 ml. per gallon in aviation gasoline.

The ether esters which are effective in increasing the octane rating of an aromatic and/or olefin-containing leaded'rgasoline have the general formula:

(R MC OOCR wherein R is a hydrocarbyl radical containing l-18 and preferably 1-10 carbon atoms, R is hydrogen or a hydrocarbyl radical containing 1-29 carbon atoms and preferably 1-12 carbon atoms and R is a hydrogen atom or hydrocarbyl radical containing 1-l2 and preferably 18 carbon atoms. Although the hydrocarbyl radicals in the above general formula can be aliphatic, cycloaliphatic or aryl radicals, they are usually aliphatic hydrocarbon radicals containing 1-10 carbon atoms or an aryl radical containing 6-8 carbon atoms. Examples of effective 1,1- ether esters are the following: l-ethoxyethyl acetate, 1- methoxyethyl acetate, l-ethoxypropyl acetate, l-phenoxyethyl acetate, l-isobutoxybutyl acetate, l-methoxypropyl propionate, l-isopropoxy-2-ethylhexyl propionate, l-ethoxyethyl decanoate, l-phenoxy-Z-methylpropyl hexanoate, and 1-allyloxy-2-methylpropyl acetate.

Ether esters having the ether and acyloxy radicals on the same carbon atom are readily prepared by a series of reactions involving formation of a vinyl ether from an alcohol and acetylene followed by addition of monocarboxylic acid to the vinyl ether to give the 1,1-cther ester. This series of reactions is illustrated by the following general equations:

ROECH-i- ROH RCH CHOR OR 11/ ROII=OHOR RCOOH RCHzG OOOR In this equation, R is hydrogen or a hydrocarbyl radical and R is a hydrocarbyl radical. The reaction of the acetylene and alcohol is carried out in the presence of a catalyst which is either an alkali metal salt, a zinc salt or a cadmium salt. The reaction of vinyl ether with a monocarboxylic acid to form 1,1-ether ester occurs readily in the presence of traces of acids or can be effected noncatalytically.

The 1,1-ether ester must be present in a leaded aro matic and/or olefin-containing gasoline in a minimum concentration of 0.1 volume percent before a significant octane appreciation is realized. Below the minimum prescribed concentration of 0.1 volume percent no octane appreciation is obtained in a leaded gasoline containing the prescribed 10 or more volume percent aromatics and/or olefins. The preferred concentration of 1,1-ether esters in the fuel compositions of the invention falls between about 0.3 and 2.0 volume percent with maximum octane appreciation usually being obtained at a concentration level between 0.5 and 1.5 volume percent. Octane appreciation is obtained with 1,1-ether ester concentrations as high as 5.0 volume percent, but economic considerations preclude the use of such concentrations in commercial fuel compositions. In addition, there appears to be a significant decrease in octane appreciation as the 1,1-ether ester concentration exceeds about 1.5 volume percent of the gasoline composition.

In Table I there is shown the effectiveness of 1,.1-ether esters in raising the octane rating of leaded fuel compositions containing the prescribed aromatic and/or olefin content. The base fuel had a Research Octane Number A (RON) of 105, comprised approximately 10 volume percent n-butane, 40 percent isobutylene-isobutane alkylate, 10 percent pentenes from fluid catalytically cracked naphtha and 40 percent heavy platformate; the base fuel contained 3 cc. of TEL per gallon. Fluorescent indicator analysis (FIA) of the 105 octane base fuel indicated an aromatic content of approximately 35 percent and an olefin content of approximately 6 percent; its initial boiling point (IBP) was F. and its end point was 367 F.

TABLE I Units Improvement in RON Eflected by 1,1-Ether Esters in Octane Fuel Increase in RON Base fuel +0.5 v. percent l-ethoxyethyl acetate 1.5

Base fuel +0.75 v. percent l-ethoxyethyl acetate 1.9

Base fuel +1.0 v. percent l-ethoxyethyl acetate.. 1.7 Base fuel +0.5 v. percent 1-allyloxy-2-methylpropyl acetate 0.5 Base fuel +0.75 v. percent l-allyloxy-2-methylpropyl acetate 0 5 The data in the foregoing table prove the octane appreciating action of 1,1-ether esters in a leaded fuel containing the prescribed aromatic and/or olefin content. Particularly significant are the results obtained with lethoxyethyl acetate where almost a 2-unit octane improvement is obtained.

In contrast with the substantial octane appreciation obtained by incorporating 1,1-ether esters in a leaded fuel containing the prescribed aromatic and/or olefin content, ether esters containing the ether and acyloxy groups on different carbon atoms were ineffective in raising the octane rating of similar type fuels. For example, Z-ethoxyethyl acetate and Z-methoxyethyl acetate were inef fective in increasing the octane rating of the leaded 105 octane gasoline employed in conjunction with the data presented in Table I.

Obviously, many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit and scope thereof and, therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A hydrocarbon fuel in the gasoline boiling range containing an organo-lead anti-knock agent, at least 10 volume percent of high octane components selected from the group consisting of olefinic hydrocarbons, aromatic hydrocarbons and mixtures thereof, and an ether ester containing the ether and acyloxy radicals on the same carbon atom in a concentration of 0.1 to 5.0 volume percent, said concentration being sufficient to effect substantial octane appreciation of said fuel said ether ester having the general formula:

0 O C R wherein R is a hydrocarbyl radical containing l-18 and preferably 1-10 carbon atoms, R is selected from the group consisting of hydrogen and a hydrocarbyl radical containing 1-29 carbon atoms and preferably l-l2 carbon atoms and R is selected from the group consisting of hydrogen and hydrocarbyl radicals containing l-12 and preferably 1-8 carbon atoms.

2. A hydrocarbon fuel according to claim 1 in which said organo-lead anti-knock agent is present in a concentration between 0.5 and 4.6 cc. per gallon.

3. A hydrocarbon fuel in the gasoline boiling range containing a tetraalkyl lead anti-knock agent in a concentration of at least 0.5 cc. per gallon, high octane components selected from the group consisting of olefinic hydrocarbons, aromatic hydrocarbons and mixtures thereof in a concentration of at 'least 10 volume percent of said fuel and an ether ester of the general formula:

wherein R is a hydrocarbyl radical containing ,l-lO carbon atoms, R is selected from the gnoup consisting of hydrogen and a hydro-canbyl radical containing 1-l2 carbon atoms and R is selected from. the group consisting of hydrogen and hydrocarbyl radicals containing 18 carbon atoms, said other ester being present in a concentration of 0.1 to 5.0 volume percent whereby substantial improvement of the octane rating of said tetraalkyl leadcontaining ttuel is effected.

4. A hydrocarbon fuel according to claim 3 in which the concentration of said ether ester is between 0.3 and 2.0 volume percent.

5. A hydrocarbon fuel according to claim 3 in which said high octane components constitute 20-s0 volume percent of said fuel.

6 6. A hydrocarbon fuel according to claim 3 containing 1.0 to 4.6 cc. of tetraethyl lead per gallon.

7. A hydrocarbon fuel according to claim 3 in which said ether ester is l-ethoxyethyl acetate.

8. A hydrocarbon fuel according to claim 3 in which said ether ester is l-allyloxy-Z-methylpropyl acetate.

References Cited in the file of this patent UNITED STATES PATENTS 1,759,331 Van Schaack May 20, 1930 2,145,889 Prutton et al. Feb. 7, 1939 2,210,942 Lipkin Aug. 13, 1940 2,403,268 Davis et a1 July 2, 1946 2,409,156 Schulze Oct. '8, 1946 2,884,315 Barnum Apr. 28, 1959 FOREIGN PATENTS 277,326 Great Britain Ian. 7, 1929 507,246 Great Britain June 13, 1939 837,965 France Feb. 23, 1939 72/,1,958 Trinidad and Tobago Oct. 9, 1958 

1. A HYDROCARBON FUEL IN THE GASOLINE BOILING RANGE CONTAINING AN ORGANO-LEAD ANTI-KNOCK AGENT, AT LEAST 10 VOLUME PERCENT OF HIGH OCTANE COMPONENTS SELECTED FROM THE GROUP CONSISTING OF OLEFINIC HYDROCARBONS, AROMATIC HYDROCARBONS AND MIXTURES THEREOF, AND AN ETHER ESTER CONTAINING THE ETHER AND ACYLOXY RADICALS ON THE SAME CARBON ATOM IN A CONCENTRATION OF 0.1 TO 5.0 VOLUME PERCENT, SAID CONCENTRATION BEING SUFFICIENT TO EFFECT SUBSTANTIAL OCTANE APPRECIATION OF SAID FUEL SAID ETHER ESTER HAVING THE GENERAL FORMULA: 